1. Field of the Invention
The present invention relates to information processing control techniques.
2. Description of the Related Art
Web application program interfaces (Web APIs) of a style called SOAP (Simple Object Access Protocol) or REST (Representational State Transfer) are often used for providing various services on the Web (Web services). Web APIs are based on communications by HTTP (Hypertext Transfer Protocol). Service providers operate as HTTP servers to provide Web APIs, while service users operate as HTTP clients to use the Web APIs.
On the other hand, examples of information processing systems or information processing apparatuses include image forming apparatuses such as laser printer (LP)s and multifunction peripheral (or multifunction printer) (MFP)s. According to these types of image forming apparatuses, an operation part that displays a screen and performs key input operations is provided independent of a body part (a controller and an engine) so as to avoid a decrease in operational response even when the operational load on the body part is high. The operation part is provided with an independent operating system (OS) such as Android (registered trademark), and operates independent of the body part.
In image forming apparatuses also provided with such an operation part, the above-described REST-style Web APIs may be used, and an application (application program) on the operation part implements functions using a Web API provided by the body part.
Common HTTP communications are based on a configuration where a server returns a response to a request from a client. Therefore, according to the architecture of HTTP communications, it is impossible in principle to notify a client of changes in status (events) that occur at random times on the server side.
A number of techniques for notifying changes in status that occur on the server side have been discussed. As a typical technique, a technique called polling, according to which a client queries a server at regular intervals to check changes in the status of the server, is commonly known.
Furthermore, techniques such as Ajax (Asynchronous JavaScript [registered trademark]+XML [Extensible Markup Language]), LongPolling, and Comet are commonly known as measures for emulating notifying a client of changes in the status of a server.